The protein actin is a major cytoskeletal component of all eukaryotic cells, serving both structural and motility-related functions. The G-actin monomer binds one ATP, which is hydrolyzed upon polymerization to polymeric F-actin. Studies in this laboratory are aimed at elucidating the detailed mechanism of polymerization, the role of ATP hydrolysis, and the cellular control mechanisms for actin assembly and disassembly.